1. Field
The embodiments described herein relate to a semiconductor memory device and a method of controlling the same.
2. Description of the Related Art
Flash memory in which memory cells having a floating gate structure are NAND connected or NOR connected to configure a cell array is well known as a conventional electrically rewritable nonvolatile memory. In addition, ferroelectric memory is also known as a nonvolatile memory capable of being accessed randomly at high speed.
At the same time, resistance varying type memory that uses a variable resistance element for a memory cell is proposed as a technology for achieving further miniaturization of memory cells. The following are known as variable resistance elements, namely: a phase change memory element that has its resistance value changed by a change in state of crystallization/amorphousness of a chalcogenide compound; a MRAM element that employs resistance change due to a tunnel magneto-resistance effect; a polymer ferroelectric RAM (PFRAM) element that has a resistance element formed by a conductive polymer; a ReRAM element that has resistance change caused by an electrical pulse application; and so on.
ReRAM generally adopts a memory cell array of a so-called cross-point type, in which wiring is shared between memory cell mats and in which a current rectifying direction of memory cells is inverted via wiring layers.